The Ecology of Atlantic Cod (Gadus morhua) in Canadian Arctic Lakes

Abstract

The range of limnological conditions that support Atlantic cod populations in meromictic Arctic lakes is known to be relatively restricted. The degree to which differences in these features, particularly in the availability of allochthonous and autochthonous prey, affect the condition and growth of cod in these populations is unknown. We compared measures of condition among three Atlantic cod populations on Baffin Island, Nunavut, to assess their relationship to differences in potentially important habitat parameters. We also compared data spanning two decades (Ogac Lake) to five decades (Qasigialiminiq) to assess the degree to which natural and anthropogenic factors may have affected these populations. In general, growth rate and asymptotic length tend to be high under situations of intense cannibalism and when alternative prey species are relatively abundant. Biotic and abiotic habitat features in Ogac Lake appear to have been relatively stable since the 1950s, although the abundance of sea urchins appears to have decreased, which may explain the observation that the incidence of cannibalism has doubled. The mean size of angled cod in Qasigialiminiq has decreased by about 10 cm over the past 20 years.